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On June 6, the American Medical Association held a media briefing on anemia, funded by an unrestricted educational grant from Amgen, Inc. Topics included anemia and heart failure and new strategies for treating anemia associated with cancer treatment.
Although anemia affects millions of Americans, it is often underdiagnosed and undertreated. According to Anemia: A Hidden Epidemic, a monograph developed by the National Anemia Action Council, anemia is often associated with chronic diseases such as heart failure and cancer. It may go undetected because it may have vague signs and symptoms that can be masked by the symptoms of the diseases it accompanies.
Recently, the American Medical Association held a media briefing on anemia, funded by an unrestricted educational grant from Amgen Inc. Topics included anemia and heart failure and new strategies for treating anemia associated with cancer treatment.
Treating anemia may benefit heart failure patients because by improving oxygen delivery to the skeletal muscles, anemia therapies may improve exercise capacity. Cardiac dysfunction can cause symptoms that include fatigue and shortness of breath, making exercise limitations and the inability to perform activities of daily living a major issue for those with heart failure, said Kirkwood Adams Jr., M.D., associate professor of medicine and radiology, division of cardiology, University of North Carolina, Chapel Hill. "From a patient standpoint, exercise limitations adversely affect quality of life. It is hard to feel good about yourself when you are chronically fatigued," he continued. "Exercise capacity is one aspect of congestive heart failure that has not received as much attention as we think it deserves."
Improving exercise capacity has thus far been an elusive therapeutic goal in heart failure. Said Adams, who is also director, heart failure program, University of North Carolina, "We can administer drugs to treat edema and favorably affect cardiac structure, but these therapies do not improve exercise capacity as much as is desired."
Anemia is also a logical therapeutic target in heart failure patients. As Adams pointed out, these patients cannot adapt to anemia as well as someone with a healthy heart. Because of damage to the heart muscle, persons with heart failure cannot compensate for anemia by increasing cardiac output, nor can they change the flow of blood in the peripheral circulation.
Erythropoietin is currently used to treat anemia in patients with end-stage kidney disease, and it may also be effective in those with heart failure. "When you give erythropoietin, you raise protein levels in the body, and hemoglobin will increase," Adams explained. "Increasing hemoglobin levels in heart failure patients may result in better tissue oxygenation, which would improve exercise capacity and possibly have a favorable remodeling effect on the myocardium." Erythropoietin therapy may improve anemia without increasing the risk of renal dysfunction, hyperkalemia, and symptomatic hypertension, he said.
Darbepoietin alfa (Aranesp, Amgen) was approved in 2001 for the treatment of anemia associated with chronic renal failure, and it may represent a new pharmacologic approach to anemia in heart failure patients. It is an erythropoiesis-stimulating protein related to erythropoietin that is produced in Chinese hamster ovary cells using recombinant DNA technology. Adams said it is longer-acting and more potent than human erythropoietin. He said he feels that future studies of anemia in heart failure patients will be conducted with darbepoietin.
Anemia is also a problem in those receiving chemotherapy for breast cancer and other malignancies, said Karen Green, M.D., assistant professor of medicine, Weill Medical College of Cornell University, New York, N.Y. Chemotherapy targets rapidly dividing cells, such as those in the bone marrow. The ability of the bone marrow to produce erythrocytes is thus impaired, leading to anemia.
In women with early-stage breast cancer, chemotherapy may be given after surgery to eradicate micrometastases, said Green, also a medical oncologist, New York Presbyterian Hospital-Cornell Medical Center. In these women, anemia is usually mild. Women with more advanced disease, however, may have a higher degree of anemia, she continued.
In cancer patients who develop anemia, erythropoietin increases hemoglobin concentration while decreasing the need for blood transfusions, thus improving their quality of life, said Green. Darbepoietin, which is in the process of undergoing FDA approval for the treatment of anemia associated with chemotherapy, was found in clinical trials to be at least therapeutically equivalent compared with erythropoietin, but it had a greater flexibility of administration. Whereas erythropoietin has to be given every week, darbepoietin can be given every two to four weeks.
Another issue of importance in cancer patients is nutritional supplementation. Persons undergoing chemotherapy should not take too many supplements, Green warned, because excess antioxidants may counteract the effects of chemotherapy and radiation. He suggested that patients discuss with their physician any nutritional supplements that they are taking or are considering.
Charlotte LoBuono. Anemia treatment can benefit patients with heart, kidney, and cancer woes.